title: Proliferation and differentiation of immature thymocytes induced by a thymic stromal cell clone.
abstract: The monolayer of our established thymic stromal cell clone (MRL104.8a) exhibited the capacity to maintain immature double-negative thymocytes. Such capacity was also expressed by a factor produced by the MRL104.8a monolayer. This factor designated as thymic stroma-derived T cell growth factor (TSTGF) was found to be distinct from IL-2 or IL-4 but similar to IL-7 of the previously described cytokines from the functional and molecular aspects. The MRL104.8a monolayer also exerted its differentiation-promoting effect on double-negative thymocytes. Culture for one day of purified double-negative thymocytes on the monolayer resulted in the induction of an appreciable per cent of CD3-4-8+ cells. This differentiation could also be induced by a semipurified TSTGF sample but not by recombinant IL-7, suggesting that the MRL104.8a cells elaborate a factor(s) responsible for initiating the differentiation of double-negative cells in addition to the growth-promotion factor identical or closely related to IL-7. When the culture period of double-negative thymocytes was extended to 2 or 3 days, an appreciable number of double-positive (CD4+8+) and single-positive (CD4+8-) cells were generated on the MRL104.8a monolayer. Thus, these observations provide strong support for the proposition that a specialized thymic stromal component plays an essential role in the intrathymic T cell development in the context of T cell growth and differentiation.
authors.affiliation: Biomedical Research Center, Osaka University Medical School, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Fujiwara
authors.forename: M
authors.initials: M
authors.lastname: Ogata
authors.forename: Y
authors.initials: Y
authors.lastname: Mizushima
authors.forename: Y
authors.initials: Y
authors.lastname: Tatsumi
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
authors.forename: T
authors.initials: T
authors.lastname: Hamaoka
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D002454:Cell Differentiation; D002455:Cell Division; D002999:Clone Cells / Q000166:cytology / Q000276:immunology; D007376:Interleukin-2 / Q000494:pharmacology; D015851:Interleukin-7 / Q000494:pharmacology; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D007376:Interleukin-2; D015851:Interleukin-7